Vented safe break terminator



R O T A ,N I

6 M6 9 KT W V E .R BW IE 5 EF 0 MM 2 1 D T N E V 4 2 5 2 O 8 Nov. 26,1968 Fl G EDWIN A. LINK BY RONALD E. BARRY Attorney United States Patent3,413,592 VENTED SAFE BREAK TERMINATOR Edwin A. Link, Waukesha, Wis.,assignor to RTE Corporation, Waukesha, Wis., a corporation of Wisconsin.

Filed Dec. 7, 1966, Ser. No. 599,772 4 Claims. (Cl. 339111) ABSTRACT OFTHE DISCLOSURE Disclosed herein is an electrical connector including aplug having a first electrically conductive member connected to a highvoltage conductor and a receptacle having a second electricallyconductive member having a passage positioned within the receptacle andbeing connected to a second high voltage conductor and means to relievepressure within said passage on insertion of said first electricallyconductive member into the passage.

This invention relates to electrical connectors of the plug-in type, andmore particularly to an improvement in a bushing for high voltageconductors to provide greater safety.

Plug-in type connectors are well known and are used extensively forconnection and disconnection of conductors. These connectors include abushing having an electrically conductive sleeve and a plug having anoutwardly projecting electrical contact. On insertion of the electricalcontact into the sleeve in the bushing an electrical connection is madebetween the two electrical members. It is well known that just prior tomaking contact between the two electrical members, the members will burncreating metal vapors which in turn spue or play on the insulatingmembers. If the insulating members are made of organic material it willalso decompose to a gaseous product. Since the bushing and plug are madeto enclose the contacts on connection, the metal vapors and gaseousproducts will be confined to the space between the bushing and plugproducing a high pressure condition which is detrimental to the safetyof the operator performing the connection. This is especiallysignificant when connecting high voltage conductors if one of theconductors is short circuited. A high fault current will be set up onprestrike increasing "vapor pressure within the space between thebushing and plug to an explosive condition.

The primary object of the present invention is to provide an electricalconnector which overcomes this hazard.

Another object of the present invention is to provide an electricalconnector for electrical conductors that provides greater safety onconnection.

A still further object of the present invention is to provide animproved safety arrangement for an electrical connector that is simplein operation and requires substantially no increase in cost.

A still further object of the present invention is to provide animproved bushing for high voltage conductors that is compatible withstandard plugs for such conductors.

A still further object of the present invention is to provide animproved bushing for connecting electrical conductors which eliminatesthe hazard of high pressure on connection of the conductor.

These objects are accomplished by improving the structural arrangementof the bushing for a plug-in type electrical connector. A passage orrecess is provided through the bushing as a continuation of a space inthe sleeve or tubular electrical contact in the bushing. The end of thepassage is either left open or an enlarged chamber or one-way valve isprovided at the end of the passage to allow for the expansion or escapeof any high pressure Patented Nov. 26, 1968 ice ' created between theelectrical contact member and the electrical sleeve located within thepassage in the bushing the increase in vapor pressure within the passagewill either expand into the enlarged chamber or will be vented toatmosphere through the one-way valve or open end of the bushing. It isalso possible to reduce the vapor pressure by cooling or condensing thevapor in the passage by positioning a mass of metallic material in thepassage. Copper wool turnings have been used successfully to accomplishthis result. A small slot or groove may be provided in the electricalcontact member to vent the high pressure gas back through the slot inthe contact member.

Other objects and advantages will become more readily apparent from thefollowing detailed description when read in connection with theaccompanying drawings in which:

FIG. 1 is a cross-sectional view of the bushing showing the expansionpassage.

FIG. 2 is a view of a modified bushing showing a oneway valve at the endof the passage.

FIG. 3 is a view of another modification of the invention showing anexpansion chamber at the end of the passage and also with a coolingmedium in the chamber.

The electrical connector shown and described herein is similar in itsbasic structure and operation to the bushing or receptacle and theelectrical connector shown and described in my copending application,Ser. No. 343,527, filed Feb. 10, 1964. As seen in the drawing theelectrical connector includes an insulating bushing 5 and a plug-in typecontact member 7 which is connected to an electrical conductor (notshown).

The bushing 10 is made from any of the known organic or inorganicinsulating materials and is shown in a cylindrical form with a mountingflange 14 provided on its outer surface. A longitudinal passage 12 isprovided through the center of the bushing. The bushing is shown in anaperture 18 of a wall 16 for a transformer or the like. A mounting clamp17 is secured to the bushing after insertion through aperture 18 andscrews 15 are turned against the wall until the flange abuts the otherside of the wall. The mounting clamp shown is an internal mount but anoutside or external mount could also be used.

An electrically conductive sleeve 20 is positioned within the passage inthe bushing and projects out of one end of the bushing. The sleeve isopen at both ends forming an open passage through the bushing. A highvoltage conductor 38 is connected to the outwardly extending end ofsleeve 20 and is held in place by brass nuts 44. An arc extinguishingsleeve 24 may be positioned at the end of sleeve 20 within the passage12 of the bushing. The plug-in type contact member 7 includes anelectrical contact member 28 which projects from an insulated housing 27and has an arc extinguishing tip 26 secured to the end of the member.The outer edge 25 of the housing is designed to engage the bushing priorto the engagement of the contact member 28 with the electricallyconductive sleeve 20. A confined chamber or space 23 is then presentbetween the housing 27 and the bushing 10 prior to the engagement of theelectrical contact member 28 and the electrically conductive sleeve 20.

When the electrical contact member is inserted into the passage in thebushing, an electrical circuit will be completed when member 28 engagessleeve 20. However, if one of the conductors is short circuited, a heavyarc may be set up between member 28 and sleeve 20 just prior to makingcontact due to the high voltage. The heat of the arc will increase thevapor pressure within the sleeve which will expand out through theopposite open end of the sleeve.

In FIG. 2 a modified arrangement of the bushing is shown with sleeve 20projecting outward from the hOuSing to a greater extent than in FIG. 1.The high voltage conductor 38 is secured to the end of the sleeve bybrass nuts 44 also as in FIG. 1. However, this bushing is designed foruse in a transformer housing where the inner end of the bushing may beimmersed in oil. The end of the sleeve is, therefore, closed at 31 andgas ports 34 are provided near the end of the passages in sleeve 20 toopen the passage to the atmosphere. A flexible sleeve 36 is mounted onthe outer wall of the sleeve 20 so that it overlies the gas ports. Thesleeve should be made of a material which has suflicient flexibility toallow vapor that is under pressure to vent out through the gas port andunder the sleeve. A sleeve of silicone rubber type valves could also beused to accomplish this same result. When the electrical contact member28 is inserted into the bushing, a small vapor pressure build up willoccur since the sleeve is closed at both ends. If there is a faultcurrent in the line upon or during connection an arc will be createdbetwen the electrical contact member and the sleeve creating asubstantial increase in vapor pressure in this space. This high pressurevapor will cause the flexible sleeve to move sufficiently in order toallow the gas to escape through the gas ports. The sleeve willimmediately close the gas ports after the gas has escaped preventing anyoil or other material from entering the bushing.

In the modification shown in FIG. 3 a portion of the sleeve 20 is shownwith an enlarged chamber 70 near the end of the passage. High voltagecable 38 is secured to the end of the sleeve by nuts 44. This chamber isdesigned to provide suflicient volume to allow any high pressure vaporcreated in the sleeve 20 to expand and thus reduce the vapor pressureand eliminate the hazard of an explosion. If the volume of the chambercannot be made large enough to allow for sufficient expansion of thevapor, a heat absorbing mass 72 may be placed in the sleeve and chamberto condense the vapors. Copper wool turnings may be used to accomplishthis result.

Referring again to FIG. 1 of the drawings, a small slot or groove 80 isshown in the electrical contact member 28. This groove may be used whereit is necessary to vent any high pressure vapor products back into thespace 23 rather than into a transformer housing. The vent or slot isonly Vs" milled cut made in the top of the longitudinal member. Itextends from the end of the arc extinguishing tip 26 back to the housing27. It is also possible to provide a slot in the sleeve 20 and areextinguishing sleeve 24 to accomplish the same result. This slot can beused with any of the other pressure relief arrangements shown in thebushings of FIGS. 1 through 3.

Although a number of embodiments of the present invention have beenshown and described it should be apparent that various changes andmodifications can be made herein without departing from the scope of theappended claims.

What is claimed is:

1. The combination with a plug having a first electrically conductivemember connected to a high voltage conductor, of means for connectingsaid member to the end of a second high voltage conductor comprising:

an electrically insulating receptacle having a passage,

a hollow electrically conductive member positioned in said passage,

said member extending through said receptacle and being connected to theend of said second high voltage conductor,

and a one way valve to relieve vapor pressure within said passage oninsertion of said first electrically conductive member into the passage,said one way valve including a number of gas relief ports in said hollowelectrically conductive member to vent said hollow member to atmosphereand a flexible sleeve overlying said ports, the flexible sleeve allowingfor the relief of gas pressure within said hollow member on insertion ofsaid first electrically conductive member into said hollow member andpreventing the ingress of any foreign matter into said hollow member.

2. The combination according to claim 1 wherein said first conductivemember includes a slot to relieve vapor pressure within said passage.

3. An electrical connector comprising:

a first housing having a first electrically conductive member therein,

a second housing having a second electrically conductive member embeddedtherein,

said first member being insertable into said second electricallyconductive member,

and relief means for relieving pressure within said second electricallyconductive member when said first member is inserted therein, saidrelief means comprising a vent in said second electrically conductivemember and a resilient sleeve closing said vent.

4. A plug having a first electrically conductive member connected to ahigh voltage conductor and an electrically insulating receptacle havinga passage,

a second electrically conductive member positioned in said passage, saidsecond member extending through said receptacle and being connected to asecond high voltage conductor and a one way valve at the end of thepassage and a slot in the first conductive member to relieve vaporpressure within said passage on insertion of said first electricallyconductive member into the passage.

References Cited UNITED STATES PATENTS 1,043,759 11/1912 Fisher.1,535,148 4/1925 De Hart 339----111 2,223,975 12/ 1940 Traver. 2,802,9988/1957 Bauer 339-1 11 3,181,103 4/1965 Fedorick 339-112 X 3,277,424 10/1966 Nelson 339-1 11 FOREIGN PATENTS 685,374 3/1930 France.

917,190 8/1954 Germany.

100,563 8/ 1923 Switzerland.

RICHARD E. MOORE, Primary Examiner.

